Production of improved cellulosic materials



Patented June 29, 1943 v l I UNITED sT Es PATENT OFFICE PRODUCTION OF l'MPROVED CELLULOSIC' I MATERIALS Richard E. Reeves, Yonkers, N. Y., assignor to The Chemical Foundation, lncorporated a corporation of Delaware No Drawing. Application May 29, 1939, 7 Serial No. 276,442

3Claims. (cl. 8-120) This invention relates to the production of cellulosic component. For example, while a preimproved textile materials. ferred method of treatment under this invention The present invention is based upon a selec may be said broadly to be a methylation; in that tive treatment of cellulosic fibers employed for it involves the use of diazometha-ne, the purpose example inthe textile industry. 5 and, effect of the treatment is entirely different It has been discovered, as is more particularly 7 from earlier procedures in which the purpose explained in the copending application of Wanda was to introduce alkyl groups directly into the K. Farr Ser. No. 270,157, that the cellulose memcellulose molecule. As"distinguished from this brane comprises essentially two constituents, the present invention relates to the enhancementcrystalline cellulose and an encasing or cement- 10 of the stability of the noncellulosic material by ing material having the characteristics of introducing alkyl or other stability-enhancing pectous materials. The cellulose material, groupings therein. which occurs in the cellulose membrane, is in the According to a preferred method under the in-' form of ellipsoid particles having the dimensions vention the cellulosic material such as cotton substantia1ly 1.1 x 1.5 mu. The cellulose parthread, woven, knitted or netted cotton fabrics ticlesar'e remarkably stable and relatively nonare treated with a solution of diazomethane, reactive and are not, "as had previously been supcontrolled as to concentration, temperature and posed, soluble'in thetypical'cuprammonium soluperiod of contact so as selectively to 'act upon tions. In the cell membranes, as for example in and modify the non-cellulosic material to therecotton fiber, the cellulose particles exist as a by pr the h mi al nd physi al haracterdeflnitelyoriented phase dispersed in a matrix lstics of the fabric. In such preferred method of'the amorphous non-cellulosic (pectous) mate-.' the fabric is contacted in a suitable vessel with rial. It was found further that many of the n' th r a s u of d a th echaracteristics, such as tensile strength, reac- In a yp al p d otton th ead was imtivity and the like, which heretofore had been 25. ed n acold solution of 20-30 Of dia oattributed to the cellulose component, were. conmethane p r liter of t in th p p rtion of trolled to no-inconsiderable degree by the nonfrom 15 tO 100 of bhe'sollltion 'l m cellulosic amorphous material. of the thread. The thread was immersed in the The present invention developed from this new S0luti0n for a period of several day Dllrlng t 1 conception of the true structure and constituency P r pe l an ly i Showed a gradual deof the cellulose membrane. Specifically th increase in concentration of the diazomethane due vention relates to a method of modifying the to the reaction as we as o s es b evaporachemical characteristics of the. non-cel1ulosic 171011 and Spontaneous deco position. The maconstituent associated with cellulose (as for exterial was t d. sh d succ ssive y ample in tt fibers) t thereby advantageouswith water, alcohol or ether and air dried.

1y modify the physical characteristics ofthe The p d thus produced was Chemically I products produced-therefrom analyzed and was found to contain methyoxyl The broad concept of the invention can best groups (551% 0CH3)- h Pr uct was then be explained by an illustrative procedure in tested, in comparison with an untreated sample which the resistance of cellulosic fabric to chemi- 0f the same material, to determine the tensile cal action is greatly increased, for example an strength before and after treatment with sodium increased resistance to tendering by hypochlohyp chlorite. The results of such tests are rite solutions. The technical value of such an Shown in the following table:

improvement is obvious.

It has been found that the chemical resistance Table I of a cotton fiber or fabric is largely a function v of the resistance of the non-cellulosic material. Tensile th It has been further found that this resistance may greatly be increased by stabilizing the ,relathread Before- 25 hrs..at tively reactive cementitious material by intro- N800 25Nwith 20 ducing additional grouping therein as for extreatment N860] ample alkyl and nitro groups.

It is to be observed at this point that the presmethylated ent invention is carefully to be distinguished Methylawd OC 12289 1,092

from earlier suggested methods of modifying the It will be observed that the described treatment measurably improves the initial tensile strength of the fabric, in the recorded test about eight per cent. The striking improvement however is in the resistance of the treated material to the deleterious action of the hypochlorite solution. As will be observed after similar treatments in sodium hypochlorite the methylated fabric was almost one hundred per cent stronger than the untreated material. of equal if not greater significance is the fact that whereas the action of the hypochlorite reduced the strength of untreated cotton to substantially one half the original value, this reagent did not materially reduce the strength of the methylated product, the reduction in strength being only about sixteen per cent.

A most interesting and highly important further effect of this type of treatment is that the treated product shows a very marked resistance to bacterial action, that is to say, to the action of the cellulose-decomposingbacteria. Such a characteristic greatly enhances the value of cotton fabrics which, as is known, are quite susceptible to the action of bacteria and mildew.

As a result of further experimentation, it was determined that the described treatment may readily be employed with all types of cellulosic material to introduce the desired group therein and thus to improve their physical and chemical properties.- The following table, in which are recorded the results of treating different types of cellulosic material with the described reagent illustrate their amenability to methylation with the concomitant advantages herelnbefore mentioned.

It will be appreciated that it is within the membrane by the introduction of a substituent group other than the methyl group, as for example other alkyl groups, nitro groups, and those of a similar character which serve to stabilize the pectous material.

It will be appreciated too that the preferred embodiment herein described presents immediate utility. A treatment of cotton fabrics of the character described increases the resistance and hence the life of such products which during normal use, as in typical laundering, are subjected to the drastic action of hypochlorite or similar bleaching solutions. The invention, therefore not only resides in the broad concept of improving cellulosic products generally, in the respects indicated, but also in the specific improvement of insuring increased longevity of cotton fabrics.

I'claim:

1. A method of treating cotton fabrics to impart thereto a marked resistance to the action of hypochlorite solutions which comprises subjecting the fabric to the action of a solution of diazomethane of a concentration of substantially from 20 to grams per liter at below room temperature in the proportion of between about 15 cc. and 100 cc. of solution to about 1 gram of the fabric treated and for a period of several days to effect selective methylation of the pectous hon-cellulosic constituent of the fabric;

stability of the non-cellulosic material of the cell 2. A method of treating cotton fabric to increase their resistance which comprises subjecting the fabric to the action of an ethereal solution of diazomethane of a concentration of about 25 grams per liter in the absence of hydrolyzing agents in the cold for a period of several days to methylate the pectous non-cellulosic constituent of the fibers of the fabric and without any substantial methylation of the cellulosic constituent of the fabric.

3. A method of treating cotton fabrics to impart thereto a marked resistance to the action of hypochlorite solutions which comprises subs jecting the fabric in the cold to-the action 'of an ethereal solution of diazomethane, of low concentration for a period of several days which will effect selective methylation of the pectous noncellulosic constituents of the fabric as distinguished from the cellulosic constituents.

RICHARD E. REEVES. 

